One big part of Dr. Ketcham's research is studying geological specimens in 3D using high-resolution X-ray computed tomography (HRXCT), which is similar to CAT-scanning for humans but is optimized for imaging higher-density objects at higher resolution. HRXCT can be used on all sorts of geological samples, from fossils to meteorites to pore networks in sandstone. Dr. Ketcham's research methods include both visualization and developing new computational tools to “mine” HRXCT data sets for quantitative data. Current and ongoing projects include measuring discrete components within a specimen volume (such as clasts, crystals, mineral grains, fluid inclusions, vesicles) to determine their locations, sizes, shapes, orientations, and contact relationships; quantifying three-dimensional fabrics such as mineral foliations and trabecular bone; and measuring fracture roughness and porosity/permeability networks.
Dr. Ketcham also works on the theory and practice of apatite fission-track (AFT) thermochronology, and deriving the thermal history of rocks (i.e. what temperatures they experienced at certain times in the past) from AFT, (U-Th)/He, and vitrinite data. He oversees the fission-track thermochronology laboratory. Ongoing projects range from gathering basic data to better understand fission-track behavior and improve how we make measurements and create interpretations, to applications in a range of geological environments, from metamorphic core complexes to the Grand Canyon.
Dr. Ketcham also conducts research on the nucleation and growth of porphyroblasts (large crystals that grow during metamorphism), combining computational models and geochemical observations test how well we really understand this fundamental geological process.